The field of dentistry has a large publication base dealing with compositions and materials for carrying out many necessary restructuring of teeth. One of the divisions of this field is in the use of adhesive materials to adhere dental structures and such materials are manufactured from acrylate chemistries.
Areas of use include cavity liners, filling materials to form composites, resin modified glass ionomers, temporary filling material, and the like.
The performance and service life of glass or ceramic filled polymeric composites in dentistry depends on the nature of the resin, the type and size of filler and interfacial phases, as well as the efficacy of the polymerization process used for curing in place.
The synergy that exists between the organic polymer matrix and the fillers is principally mediated by the interfacial interphasial phases of the mix. This latter phase develops as a result of the dual reactivity of silane coupling agents such as XRSi(Z)3, a tri alkoxy functional molecule capable of reacting with the silanol groups of glass or ceramic fillers, upon hydrolysis of the alkoxy groups of the silane to form silanols and —Si—O—Si— bonds to filler surfaces, and also with the resin phase by graft copolymerization via the functional group, usually a methacrylic or vinyl group.
Thus, silanes per se are well-known in dentistry for bonding and adhesion. The chemistry of organofunctional silanes can be quite complex, involving hydrolytically initiated self-condensation reactions with or without solvents that culminate in polymeric silsesquioxane structures. This can also involve exchange reactions with hydroxylated or carboxylated monomers to form silyl ethers and esters, as well as the formation of silane derived interfaces, by adhesive coupling with siliceous mineral surfaces.
Most all of dental restoratives are multiphase materials having a composite microstructure involving one or more interfaces or interphases. With regard to composites, the term interface is reserved for the relatively sharp boundary layer that exists between the continuous or matrix phase and the dispersed or filler phase of these heterogeneous materials. In many composites, however, the microstructure is characterized by a broad, more gradient like transition zone that forms between the continuous and dispersed phases that is more accurately referred to as an interphase. For example, this diffuse type of interphase is characteristic of acid-base type dental cements, e.g. carboxylate and glass-ionomer cements, especially the latter. The sharp type of interface is more characteristic of amalgams and resin-base, macro-sized glass or ceramic filled composites.
Aspects of the instant invention is based on reactive silicates that can replace the current prior art silane and/or acrylate, glass ionomer, chemistries, or they can be used with such acrylate and glass ionomer chemistries to provide superior materials for adhesion and composite materials. The compositions and methods of the present invention are directed toward these, as well as other, important ends.